Is there a better way to avoid 'Sign comparison' warning when comparing NSIndexPath's row and NSArray count?

Question

I turned 'Signed Comparision' (aka -Wsign-compare) warnings for my iOS project in XCode (surprisingly, it was off by default). After that lots of warnings like this appeared:

/Users/michalciuba/projects/GlobeMobile/Classes/ACMailController.m:86:19: Comparison of integers of different signs: 'NSInteger' (aka 'long') and 'NSUInteger' (aka 'unsigned long')

They are usually caused by comparing row property of NSIndexPath which is NSInteger to the value returned by 'count' method of NSArray, like this:

if(indexPath.row < [self.myDataArray count]) 

The warning can be simply fixed by casting:

if(indexPath.row < (NSInteger)[self.myDataArray count]) 

However, it has to be done if every single place where such values are being compared. And they are being compared in dozens of places. I wonder if there is a better and more clever way to solve this problem? I don't want to turn off this warning, because it may help to prevent issues like unsigned integer underflow.

Koroseal

Try with if(indexPath.row <= self.myDataArray.count-1) – Liverish

This will still trigger a warning. And it will fail when myDataArray is empty (because of NSUInteger underflow). Actually this is why I turned this warning on :) – Hort

Answer 1

You could implement a category that does it for you :

@implementation NSArray (SignedCount)

- (NSInteger) signedCount
{
    NSInteger count = (NSInteger)[self count];
    return count;
}

@end

Monophysite